The present invention resides in a method and apparatus for cutting sheet material having at least one layer of adhesive bonded to it and cut either as a ply or a stack of plies of material during a cutting operation, and deals more particularly with an improvement in such an apparatus and method whereby a means is provided for treating the knife blade of a cutter as cuts are made during a cutting operation to prevent adhesive buildup on the blade surfaces and on grinding stones used to sharpen the blade intermittently during the cutting operation.
In cutters of the type wherein a blade is reciprocated to cause cutting of the cloth material along a path in which it is moved, the reciprocation rate of a knife blade may be such that it produces enough heat in a cutting operation to cause the cut material to be fused, such as in the case where a vinyl material is being cut. In U.S. Pat. No. 3,830,122 issued to Pearl on Aug. 20, 1974, this problem is addressed and is remedied by providing a liquid coolant to the cutter head thereby conducting heat away from the blade to effect better performance of the cutting machine. However, in the case where cutting occurs in materials, such as used today in the automobile manufacturing industry wherein a fabric or vinyl sheet having an adhesive backing is cut, the blade is dulled by adhesive which adheres to its surfaces as cutting progresses. Also, in cutting materials, such as trilaminates, wherein a powdered fusible adhesive is interposed between two outer plies, adhesive which is either active or caused to be activated by the effects of friction generated by the blade deposit on the knife edge thereby dulling it and decreasing knife performance in the cutting operation.
This problem is not just limited to build up of adhesive on the cutting blades. Cutter heads which employ a reciprocating blade suspended from a carriage moved over a layup, also employ grinding stones which are carried by the carriage and rotate about given axes when brought into engagement with the knife blade to sharpen it. One such example of a sharpening apparatus of this type is disclosed in U.S. Pat. No. 4,033,214 issued to David Pearl on Jul. 5, 1977. As disclosed in this patent, the blade is sharpened by bringing the rotating grinding stones into engagement with the knife blade while reciprocating the blade to sharpen it along its length. During this process however, any adhesive previously adhering to the blade is transferred to the grinding stones and thereafter becomes lodged in the grinding surfaces of the stones, thereby reducing the abrading effectiveness of the sharpening mechanism.
Accordingly is an object of the present invention to provide a means in a cutter whereby the blade of the cutter is continuously treated to prevent the adhesion and subsequent build up of adhesive or other like material on the blade surface.
It is another object of the present invention to provide a means employed in a cutter of the aforementioned type wherein the blade is reciprocated through a stroke and wherein the means for treating the blade is provided as a lubricating means located along the stroke of the blade such that with each reciprocation of the knife blade, the lubricant is applied and is subsequently wiped from the blade surfaces which cut the material.
It is yet a further object of the present invention to provide a lubricant of the aforementioned type and cause the lubricant to be applied to the grinding stones of a cutter head to dissolve adhesive transferred thereon from the blade and/or keep clean the grinding surfaces to avoid build up of an adhesive or other foreign material which otherwise would be transferred from the blade to the grinding stone.